The power supply in a computer is connected to other peripheral devices such as VGA cards, HDD, RAM, CDROM, DVD and the like through a power supply transmission cord to deliver electric power. The stability of the transmission cord is very important. When the power supply delivers electric power, ripples and noises often occur. On the other hand, signal transmission of the VGA card generates high frequency noises. The power supply transmission cords now on the market to connect the power supply of the computer and the peripheral devices such as the VGA cards, HDD, RAM, CDROM, DVD and the like do not have any apparatus to filter out high frequency noises and ripples and other noises. As a result, the screen often has undesirable display such as snow flakes or skewed lines. This could shorten the life span of the peripheral devices such as the VGA cards, HDD, RAM, CDROM, DVD and the screen. Display quality of the screen also is affected.